Distributed networking environments, such as enterprise computing environments, generally consist of individual interconnected subnetworks. These subnetworks include intranetworks physically defined within a geographically limited area, such as within an office building, and internetworks, including the Internet, physically defined over a geographically distributed area using private and leased terrestrial lines and via satellite communications links.
Commonly, both intranetworks and internetworks operate in accordance with the ISO/OSI open interconnect model, an international network protocol definition, which specifies seven hierarchically-related network layers for use in digital data exchange. The Transmission Control Protocol/Internet Protocol (TCP/IP) standard defines a complementary layered network protocol, which simplifies the ISO/OSI interconnection model. TCP/IP is described in W. R. Stevens, “TCP/IP Illustrated, Vol. 1, The Protocols,” Chs. 1-3, Addison Wesley (1994), the disclosure of which is incorporated by reference.
TCP/IP is a layered network protocol framework and specifies media access, link, network, transport, and application protocol layers. The link and network layers define point-to-point protocols and the transport and application layers define end-to-end protocols. Applications executing within the application layer exchange packets containing source and destination addresses to identify originating and receiving hosts. The remaining network protocol layers facilitate the physical and logical transport of each packet.
The flow of packets can be controlled during transit to accommodate available network bandwidth and rate capabilities. A traffic manager can be co-located at a network domain boundary to monitor and analyze transient packet traffic for use in traffic analysis and flow control. Traffic managers primarily optimize throughput through bandwidth and rate control applied to internetwork connections, which are more costly yet slower than intranetwork connections.
Throughput optimization is particularly important in a high-traffic environment, such as a corporation, university, or Internet service provider. Unmanaged network traffic, particularly at the application network layer, hampers efficient throughput utilization and can result in bandwidth lost to non-core network traffic. Traffic managers can address application network layer throughput by prioritizing traffic according to user-specified network policies to ensure network availability for core network traffic needs.
Certain network protocols make throughput optimization difficult. The Transmission Control Protocol (TCP), for instance, provides end-to-end connectivity between origin and destination hosts. TCP is used by application layer protocols, such as the Hypertext Transport Protocol (HTTP), to exchange information between application programs. TCP is greedy and consumes available bandwidth. A TCP connection will initially send one packet, followed by two packets, and so on, to incrementally increase the packet rate until no further gains are realized. Unmanaged TCP connections can dominate traffic flow and monopolize available bandwidth.
Data compression can increase total utilization of bandwidth, but does not stop the greedy nature of TCP/IP connections. Data compression can be combined with rate control to meter the pace at which packet traffic flows over a network. Rate control helps to alleviate bottlenecks and controls greedy flows by managing per-flow bandwidth while data compression allows smaller packets to be sent, thereby conserving available network bandwidth. This marriage of the two functions allows per-flow and aggregate management of bandwidth with visibility into the effects of the compressions.
In the prior art, data compression has been used as the principal means to increase bandwidth utilization. However, prior art data compression solutions fail to control flow rates entering into a compressed stream of data and fail to provide means for changing or removing data compression midflow. In addition, when used in conjunction with non-integrated bandwidth management solutions, prior art data compression solutions are unable to completely utilize the bandwidth available on a datalink over which traffic is classified.
Therefore, there is a need for an approach to providing an integrated solution that provides packet flow management controlling both aggregate and per-flow bandwidth in concert with data compression to optimize the throughput and utilization of a datalink.
There is a further need for an approach to shaping packet traffic exchanged between end-to-end hosts. Preferably, such an approach would allow the traffic streams to be controlled collectively and individually.
There is a further need for an approach to providing flexible and granular data compression on per-flow, per-service and multiple shared-service bases. Preferably, such an approach would allow the form of data compression to be changed or eliminated midflow.